1 84 E. A. STEPHENSON 



At the suggestion of Professor W. H. Emmons, the writer began 

 in 191 2 a series of investigations of a hydrothermal character with 

 particular reference to the geologic application of the results. It 

 was hoped to contribute something concerning the temperatures, 

 pressures, nature, and concentrations of the solutions which produce 

 new materials from the feldspars and from some of the ferromag- 

 nesian minerals. 



PLAN OF THE WORK 



The plan of the work has been to try the effect of various simple 

 dilute solutions upon the feldspars and one ferromagnesian mineral 

 at various temperatures and pressures. This has been done up 

 to 280 C, at intervals of about 50 . It is planned to work on up 

 to about 500 C. if the results justify such a course. The solutions 

 have been tried at various concentrations, for different lengths of 

 time, besides the different temperatures. 



The minerals used have been nearly pure species. A high-grade 

 adularia from the St. Gotthard tunnel, albite from the Amelia 

 Court House locality, orthoclase from Elam, Delaware County, 

 Pennsylvania, microcline from C. A. F. Kahlbaum (locality not 

 known), and an aluminous hornblende from Renfrew, Ontario, 

 Canada. These have in all cases been powdered to pass a 100- 

 mesh sieve, and portions exactly or approximately one gram in 

 weight have been used for each experiment. 



THE OVEN 



For work at temperatures above ioo° C, the oven described as 

 follows was constructed (Fig. 1). A box 28^X15X16 inches (out- 

 side measurements), made of sheet iron, is fastened at the edges to 

 a similar box 26^X13X15 inches placed inside of it, with the space 

 between packed with asbestos. A door at the front extends the 

 full length and height of the oven, opening outward with hinges 

 along the bottom. Two holes are cut in the top at H and H', 

 Fig. 2, for the insertion of thermometers. A number of holes, 

 and 0', about 1^ inches in diameter are also cut in one end of the 

 box, Fig. 3. When the oven is in use these holes are closed with 

 loosely packed asbestos wool. 



